Basic Syntax highlighting, added CodeTextBox to MainWindow to test it.

Befunge/Editor/CharStyles/ITextStyler.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Documents;
+
+namespace Befunge.Editor.CharStyles
+{
+    public interface ITextStyler
+    {
+        IEnumerable<Run> StyledString(string input);
+    }
+}